Package and electronic device

A package has a cavity to be sealed by a lid. The package includes a heat sink having a coefficient of thermal expansion of 9 ppm/° C. or more and 15 ppm/° C. or less from 25° C. to 100° C. and a frame disposed on the heat sink, made of ceramics, and surrounding the cavity in plan view. An outer edge of the frame includes a first linear portion extending along a first direction, a second linear portion extending along a second direction orthogonal to the first direction, and a chamfer connecting the first linear portion and the second linear portion in plan view.